Some will say the standard expander can be used. Maybe...try it slowly with lube. An intermediate size (8mm or 338) may make it easier.
A file, a drill motor, & some fine wet/dry paper oiled may be useful for reducing the blunt end of a non tapered expander. Most, if not all, quality die makers have tapered expander balls available for a few $$. A newer Redding set has a tapered expander from the factory.
If using new brass annealing shouldn't be needed.
